soil - Lublin

strength of the already existing structure unit, several more general but detailed
accounts are available in the international literature, which has also been dealt with
in the present paper. The presented results found in the literature verify the idea
that processes of aggregation do affect the availability of water for plant uptake and
the accessibility of water-filled pores for roots, which is reduced owing to the formation
of finer pores where water is available only at more negative pore water
pressures. If the processes of aggregate formation under mechanical and biological
conditions are combined with the corresponding effects on hydraulic and aeration
properties, it can be in general concluded that there is never constancy at the beginning
of soil structure formation but it is only reached after a longer period, i.e. at
the smallest free entropy (Table 2).
REFERENCES
1. Currie, J.A. 1965: Diffusion within soil microstructure. A structural parameter for
soils. Soil Sci. 16,278 – 289.
2. Glinski, J., and W. Stepniewski 1985: Soil aeration and its role for plants. CRC Press,
Bocca Raton.
3. Greenwood, D.J. and D. Goodman 1967Direct measurement of the distribution of oxygen
in soil aggregates and in columns of fine soil crumbs. J. Soil Sci., 18, 182 - 196
4. Horn, R. 1976: Festigkeitsänderungen infolge von Aggregierungsprozessen eines mesozoischen
Tones. PhD Thesis University Hannover.
5. Horn, R. and A.R. Dexter 1989: Dynamics of soil aggregation in an irrigated desert
loess. Soil Till. Res. 13,252 – 266.
6. Scheffer/Schachtschabel 2002: Lehrbuch der Bodenkunde, 15.Ed. Spektrum Publ.,
Heidelberg.
7. Sextone, A.J., Revsbech,N.P., Parkin,T.B. and Tiedje,J.M. 1985: Direct measurement
of oxygen profiles and denitrification rates in soil aggregates. Soil Sci. Soc. Amer. J.,
49, 645 – 651.
8. Stepniewski, W., Zausig,J., Niggemann,S., and Horn,R.1991: A dynamic method to
determine the O 2 partial pressure distribution within soil aggregates. Z. Pflanzenern. u.
Bodenkunde, 154,59 – 61.
9. Zausig, J., Hell, U., and R. Horn 1990, Eine Methode zur Ermittlung der wasserspannungsabhängigen
Änderung des Sauerstoffpartialdruckes and der Sauerstoffdiffusion
in einzelnen Bodenaggregaten. Z. Pflanzenern. u. Bodenkunde, 153, 5 – 10.
10. Zausig, J., Stepniewski, W., and Horn, R. 1993: Oxygen concentration and redox potential
gradients in different model soil aggregates at a range of low moisture tensions.
Soil Sci .Soc. Amer. J. 57, 908-916.
85